NHC配位子を用いたNi触媒による1,3-ジエンとアルデヒドの分子内環化反応の検討

抄録

A nickel(0)-catalyzed cyclization of ω-formyl-1,3-dienes using N-heterocyclic carbenes (NHC) as a ligand was investigated. When a substrate having a terminal diene moiety was treated with a catalytic amount of Ni(NHC) complex in the presence of silane, the cyclized product having a terminal olefin in the side chain was obtained, which would be produced via a five-membered nickelacycle intermediate. On the other hand, the reaction of a substrate having a phenyl, a silyl, or a vinyl group on the terminus of the diene moiety gave the cyclized product having an internal Z-olefin in a highly stereoselective manner, respectively, which would be formed via a seven-membered nickelacycle intermediate. These results indicate that the substituent on the 1,3-diene moiety in the substrate strongly would affect the stability of nickelacycle intermediates, which resulted in altering the stereoselectivity of the products.

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